Communications

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Communications

• David Patterson
• Taylor University

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Taylor University Heritage
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Taylor University Heritage NS3 TEST

• Finalist in NS3 competition
• Built on previous Taylor University student
  satellite projects
• Started serious undergraduate student interest in
  space science research
• Implemented cube-based construction
• Implemented Freewave radios

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Taylor University Heritage H.A.R.P.

• Taylor University High Altitude Research Platform
• Funded by INSGC 5 years running
• Over 65 successful high-altitude balloon missions
• 100 recovery record
• Altitudes of 100,000 feet
• Freewave radios primary up/down link
• Link distances of 200 km

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Taylor University Heritage H.A.L.O.

• Taylor University / StratoStar High Altitude
  Launch Opportunity
• Funded by INSGC 2007
• HALO II funding pending
• Coordinated launch of 8 high-altitude missions
  from Iowa to Ohio
• Successful high-altitude network
• Uses Maxtream radios for network link and
  telemetry

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BUSAT Communications Requirements
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BUSAT Communications Design

• Purpose to offload instrument data to ground
  and to receive commands from ground
• Design Redundant two transceiver
• FreeWave 900 MHz 56kbits/s Primary
• Maxstream 900 MHz 4.8kbits/s Beacon
• Heritage designs from the NS3 TEST spacecraft
• Two antennas
• Dipole antenna for primary up/down link
• Dipole antenna for telemetry beacon
• Ground station at BU
• 2m parabolic antenna currently on top of
  Photonics Building
• BUCentral command center
• Automated ground software
• Other specifications
• Power 3W (satellite side)
• Mass 0.4kg (satellite side)

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Primary Up/Down Link

• 900 MHz ISM band FHSS data radio
• 2W max output power
• Fully Doppler compensated to/- 8200 m/s
• Power (at 12V DC, 2W Tx)
• 500mA nominal transmit current
• 78mA nominal full receive
• 57.6 kb/s throughput
• Spaceflight proven

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Telemetry Beacon

• Autonomous beacon
• Requires only 5V input to function
• 900 MHz ISM band FHSS data radio
• 1W max output power
• Power (at 5V DC, 1W Tx)
• 730 mA nominal transmit current
• 80 mA nominal full receive current
• Satellite health monitor
• 5V and 12V line monitor
• Communications subsystem temperature
• CubeSat potential

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Power / Beacon Board, RF Splitter

• Two Murata NFM21PC104R1E3 EMI filters
• One on 5V, one on 12V
• Beacon generation
• Already developed for high-altitude balloon
  missions
• 12-bit analog data
• Collision protected
• RF Power Splitter
• Provides outputs to two antennas per radio
• Flight hardware will be customized to minimize
  loss in our frequency band

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Interface

• Simple, Robust Interface
• Power
• 5 and 12, filtered internally
• Command / Telemetry
• RS422 standard (differential)
• Dedicated lines
• Direct-to-radio connection from DPU
• Beacon
• No external data connection
• Antennas
• 4 SMA outputs (2x each radio)